Medium for a color changer

ABSTRACT

A flexible medium for a scrolling color changer and method of making thereof. The medium is made by applying an ink using a Meyer Rod which has varying cell lengths along its length. This leaves varying size cells of ink at different locations along the length of the medium. The ink has special characteristics whereby its evaporation rate and viscosity are carefully controlled. The viscosity is such that an amount of levelling will occur will be equal to the distance between any cells, but that cell to cell levelling will not, in general, occur.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. application Ser. No.09/572,045, filed May 16, 2000, which is a divisional of U.S.application Ser. No. 08/859,770, filed May 21, 1997, which is adivisional of U.S. application Ser. No. 08/790,235, filed Jan. 28, 1997,which is a divisional of U.S. application Ser. No. 08/286,969, filedAug. 8, 1994.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention teaches an improved flexible medium for ascrolling-type color changer. More specifically, the present inventiondefines a color changer medium with continuously-variablecharacteristics across its length.

[0004] 2. Background Information

[0005] Stage lighting systems project a beam of light which has beencolored by a color filter. Different ways of coloring the light areknown.

[0006] One way of coloring the light is by using dichroic filters suchas taught in U.S. Pat. No. 4,800,474. This technique mounts a number ofdichroic filters on rotatable color wheels. This system needs a largeamount of space because the wheels must each have room for many filtersto allow enough colors, and there must be room for the wheels to rotate.

[0007] Another way of coloring the light is by using a scrolling-typecolor changer such as that shown and described in U.S. Pat. No.5,126,886, the disclosure of which is herewith incorporated byreference. Scrolling color changers move material between two scrolls toprovide a desired filtering effect within the light path.

[0008] A problem occurs in determining how to appropriately change thecolor across the length of the color media of a scrolling changer. U.S.Pat. No. 5,126,886 demonstrates one conventional method of changing thecolor saturation across the length of the filter. A filter material isformed with a baseline saturation. A half-tone pattern is locatedthereon. This half-tone pattern provides a filtering effect which can bechanged by adjusting the number of patterned elements per unit area.

SUMMARY OF THE INVENTION

[0009] The present invention goes against this established teaching byproviding a continuously-varied color media. The color media is formedusing a specially designed “Meyer Rod” to adjust the thickness of thecoating deposited on the film.

[0010] The ink solution according to this invention has specialcharacteristics of viscosity and evaporation rate. The viscosity iscontrolled such that ink in at least one of the cells flows to the nextcell only, and not more than that amount, in the amount of time it takesthe ink to dry. This forms a continuous coating that varies in thicknessalong a gradient axis.

[0011] Thicker coatings provide a more saturated color. The thickness ofthe coating is allowed to vary between cells, but does not vary acrossthe width of the medium.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] These and other aspects of the invention will now be described indetail with reference to the accompany drawings, wherein:

[0013]FIG. 1 shows the layout of the basic scrolling color chamber usedto hold the medium made according to the present invention;

[0014] FIGS. 2A-2H show various exemplary locations of the two scrollsused according to the present invention to obtain the most importantcolors;

[0015]FIG. 3 shows the preferred technique of applying the material tothe substrate according to the present invention;

[0016]FIG. 4 shows a cross-sectional view of the Meyer Rod of FIG. 3along the line 4-4;

[0017]FIG. 5 shows the interim product showing cells of ink on thesubstrate after the Meyer Rod has passed but before the cells have hadtime to level; and

[0018]FIG. 6 shows the final levelled product.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0019]FIG. 1 shows a basic scrolling color changer according to thepresent invention. More details about the operation of such a colorchanger are found in U.S. Pat. No. 5,126,886. The first media 100 of thecolor changer extends between roll 101 and roll 102. The second media104 extends between rolls 105 to 106. The two rolls of either pair(101/102 and 105/106) are commonly controlled by gears, e.g., 110, whichallows both rolls to move in synchronism. By actuating motor 112, forexample, rolls 101 and 102 can be moved to quickly locate the colorchanger material to a desired location.

[0020] The beam of light is shown through location 114, and adjusted bya combination of the two current positions of the scrolls. The colorchanging capability is obtained by various combinations of the colors ina conventional way.

[0021] FIGS. 2A-2H show the various ways in which the colors areobtained according to the present invention. Scroll 100 is shown at thetop of each of FIGS. 2A-2H, and includes portions with varyingsaturations of yellow at a first end 200, a clear portion in its center202, and varying saturations of magenta at a second end 204. The secondscroll 104 also includes magenta at a first end 206, is clear in itscenter 208, and cyan portions at the other end 210. FIG. 2A shows thelight beam 212 passing through the two clear portions to obtain a clearlight beam 214. FIG. 2B shows how cyan and magenta are combined toobtain blue light beam 220. FIG. 2C shows cyan and clear being combinedto obtain cyan light beam 222. FIG. 2D shows cyan and yellow beingcombined to obtain a green color light beam 224. FIG. 2E shows clear andyellow being combined to obtain a yellow light beam 226. FIG. 2F showsmagenta and yellow being combined to obtain red at 228. FIG. 2G showsmagenta and clear being combined to obtain magenta 230, and finally,FIG. 2H shows cyan and magenta being combined to obtain another blue,232. The scrolls are appropriately positioned to obtain the desiredcolor light.

[0022] The actual scroll material is formed of a polycarbonate,polyester or polypropylene film coated with a special colored ink. Thecolored ink has controlled evaporation and viscosity characteristicswhich allows continuous coating. For purposes of this specification, theterm ink will be used to denote the material which is spread on thepolypropylene backing sheet. Ink includes dye molecules, which form thecolor, in a binder which holds the dye molecules in solution, and asolvent. The ink binder is typically polyester. The dye molecules in thebinder gives the material its final color. The solvent keeps the ink ina fluid state until the solvent evaporates. Therefore, when the solventevaporates, the remaining dye molecules and binder are completely dried.

[0023] The polyester binder is in a solvent-based solution. The solventincludes Methyl Ethel Keytone (MEX) and Toluene. The proportion of MEXto Toluene controls the rate of evaporation and levelling of the coatingsolution. The thickness of the ink on the polyester film controls thesaturation of color; the thicker the coating, the more saturated thecolor becomes.

[0024] Any commercially available ink can be used if the viscosity ofthe solution and rate of evaporation is controlled. The preferred inksused according to the present invention are described herein. The ink isapplied in cells as described herein, and the viscosity of the inksolution is controlled such that the amount of ink levelling betweencells which occurs in the amount of time that it takes the ink to dry,closely matches the distance between cells. For at least one of thecells, the amount of ink levelling before ink drying is precisely equalto the distance between cells.

[0025] The preferred embodiment of the present invention uses aspecially-constructed Meyer Rod to apply the ink to the substrate. Aprior art Meyer Rod used a stainless steel cylindrical rod with astainless steel wire wrapped-tightly around its circumference from oneend to the other end. The space between adjacent wires holds ink. Theamount of the coating deposit depends on the wire diameter or gauge.Typically, the coating is applied to the substrate by passing thesubstrate through a vat of ink solution, and then using different MeyerRods to squeegee off all but the amount between the wires if the Meyerrod as the film passes by it. The space between the wire curvaturesallows a specific amount of the solution to remain, and thereby leavescells of material on the substrate. Different wire gauge Meyer Rodsleave a different amount of solution on the substrate. Each Meyer Rodleft a different thickness of material.

[0026] The present invention uses a Meyer Rod of a special type tospread the ink along the substrate material in a way that itcontinuously varies along a gradient axis thereof. I considered the ideaof forming a Meyer Rod with varying diameter wire. However, I determinedthat constructing a Meyer Rod that used a length of wire with changinggauge would not be practical by itself since it would produce a conicalrod which got larger as the gauge of the wire increased. I thereforedecided to machine or precision grind a rod directly from stainlesssteel, simulating the changing wire curvature, but compensating for thechanging radius to end up with a cylindrical form. I therefore inventedthe Meyer Rod which is shown in FIG. 3 with a cross-section along theline 4-4 being shown in FIG. 4.

[0027]FIG. 4 shows the overall diameter 400 of the rod which stays thesame from-its leftmost end 402 to its rightmost end 404. Overalldiameter here refers to the diameter of the outermost edge of eachsection 406 relative to the central axis 401. However, the diameter ofthe various sections 406 vary from one end to the other. Each of thesections 406 is defined by three coordinates: x, y, and r. The originis, for example, shown at point 408, in the center of the a smallestsection 407. Hence, the section 407 has x, y coordinates 0,0, and aradius r of 0.10. The second Meyer Rod section 410 is at position 0.021,0.001 with a radius 0.011. These values are just exemplary, and for asix inch rod, I would start with a radius of 0.025 inch, and incrementeach successive radius by 0.001 inch.

[0028] The Meyer Rod operates by allowing ink to remain only in theinterstices 412 between two successive Meyer Rod portions, e.g. 410 and414. As the portions get larger in radius, the amount of ink left by theinterstices also gets larger. This means that the portions of inkdeposited by the Meyer Rod at end 402 are smaller than the portionsdeposited at the end 404. Each portion of ink left by the area betweentwo successive Meyer Rod sections will be referred to herein as a cell.

[0029] After the Meyer Rod has passed, the interim product is as shownin FIG. 5. A number of cells of ink remain on substrate 520. Eachsuccessive cell is slightly different in volume than the next cell. Forexample, Cell 502 has slightly more volume than cell 500. Of course,FIG. 5 shows an exaggeration of this phenomena.

[0030] According to the present invention, I select inks which have aviscosity such that the amount of levelling between cells in the time ittakes the ink to dry is equal to the levelling necessary for the twolargest cells. More generally, however, the viscosity must be such thatthe amount of levelling in the time it takes the ink to dry is equal tothe distance be tureen any desired cells Height 600 shows thefinally-levelled height at the highest end. Therefore, in the amount oftime it takes the ink to dry, levelling by an amount of distance shownas 508; the distance between the highest level 504 and the final height600, must occur. This may allow some cell-to-cell levelling in thesmaller portions such as 500 and 502. However, this trade-off allows allportions to level somewhat, but still to form a material which isthicker at end 600 than it is at 602. It is most important that thecell-to-cell levelling be minimized so that the thickness, and hencecolor saturation, varies along the gradient axis 604. FIG. 6 shows theportions after levelling.

[0031] The characteristics of the ink are therefore crucial. Theviscosity of the ink material is proportional to the solid content, tothe dye and to the binder. It is also proportional to a ratio betweenthe solids and the binder. The binder is typically a polyester material,such as Vitel™. I have used two preferred solvents, one of which is acombination of MEK and Toluene. The ratio between these two controls theamount of evaporation which occurs. I have also used a propylacetatesolvent.

[0032] According to the present invention, the properties of the ink arecontrolled such that its viscosity is controlled relative to itsevaporation time to provide a controlled amount of levelling. FIG. 6shows the finally levelled product. In FIG. 6, the discontinuousportions such as 500 and 502 have been smoothed into a continuousportion. The height 600 is also shown in FIG. 5. The height 504 ofportion 506 must be decreased by an amount 508 to level the finalmaterial at the height 600. Therefore, the viscosity of the materialmust be such that it can level by an amount 508 in the amount of time ittakes for the solvent to evaporate. Some example formulations aredescribed herein:

[0033] YELLOW:

[0034] The “solids” portion of the yellow ink solution have thefollowing make up:

[0035] 8.5%—Yellow pigment 83 (C-1. #21108)

[0036] 91.5%—Binder (Polyester Resin)

[0037] The “solvents” portion of the yellow ink solution has thefollowing make up:

[0038] 1.60%—Ethyl Alcohol

[0039] 15.62%—Ethyl Acetate

[0040] 21.67%—Toluene

[0041] 21.97%—Isopropyl Alcohol

[0042] 39.14%—Isopropyl Acetate

[0043] The “solids” and “solvents” are combined in the ratio of:

[0044] 25.91%—Solids (pigment/binder)

[0045] 74.09%—Solvents

[0046] This solution will have a viscosity of 57 seconds measured with822.

[0047] CYAN:

[0048] The “solids” portion of the cyan ink solution has the followingmake up:

[0049] 10.1%—Blue 15: 4 (C. I. #74160)

[0050] 0.1%—Violet 23 (C. I. #51319)

[0051] 89.8%—Binder (Polyester Resin)

[0052] The “solvents” portion of the cyan ink solution has the followingmake up:

[0053] 0.26%—Ethyl Alcohol

[0054] 0.30%—Ethyl Acetate

[0055] 1.73%—Isopropyl Alcohol

[0056] 24.63%—Toluene

[0057] 73.08%—Isopropyl Acetate

[0058] The “solids” and “solvents” are combined in the ratio of:

[0059] 27.55%—Solids (pigment/binder)

[0060] 72.45%—Solvents

[0061] This solution will have a viscosity of 37 seconds measured with822.

[0062] MAGENTA:

[0063] The “solids” portion of the magenta ink solution has thefollowing make up:

[0064] 9.6%—Rabine Red (C. I. #28620)

[0065] 91.4%—Binder (Polyester Resin)

[0066] The “solvents” portion of the magenta ink solution has thefollowing make up:

[0067] 0.24%—Ethyl Alcohol

[0068] 0.32%—Ethyl Acetate

[0069] 1.54%—Isopropyl Alcohol

[0070] 23.50%—Toluene

[0071] 74.40%—Isopropyl Acetate

[0072] The “solids” and “solvents” are combined in the ratio of:

[0073] 28.30%—Solids (pigment/binder)

[0074] 71.70%—Solvents

[0075] This solution will have a viscosity of 65 seconds measured with#2Z.

[0076] Although only a few embodiments have been described in detailabove, those having ordinary skill in the art will certainly understandthat many modifications are possible in the preferred embodiment withoutdeparting from the teachings thereof.

[0077] All such modifications are intended to be encompassed within thefollowing claims.

[0078] Although the present invention has been described using a MeyerRod, it should be understood that other techniques of ink imprintationof a backing material, including but not limited to a gravure cylinderand the like, could also be used for depositing the ink, so long as theink is applied in cells, and allowed to level between the cells.

What is claimed is:
 1. A device and/or method substantially as shown anddescribed.